least common denominator

Meaning

1. 1nouncountablemathematics

   The smallest whole number that can serve as a common denominator for two or more fractions.

   Grammar: Use with fractions; after finding it, rewrite each fraction so its bottom number matches it.

   Patterns

   • find the least common denominator
   • use the least common denominator
   • rewrite over the least common denominator

   For 1/3 and 1/4, the least common denominator is 12.

   To add the fractions, first find the least common denominator.

   The teacher asked us to rewrite each fraction over the least common denominator.

Common combinations

find the least common denominator

Find the least common denominator before adding the fractions.

common denominator of fractions

The common denominator of 1/2 and 1/5 is 10.

rewrite over the LCD

Rewrite 3/4 and 5/6 over the LCD before comparing them.

Synonyms and how they differ

lowest common denominator

A common alternative name for the same arithmetic idea; outside math it can also mean the crudest shared appeal.

least common multiple

Related: the LCD is the least common multiple of the denominators, not of the fractions themselves.

Word family

denominator noun

The bottom number of a fraction.

numerator noun

The top number of a fraction.

common multiple noun

A number that is a multiple of each number in a set.

Commonly confused: least common denominator or least common multiple? least common denominator or lowest common denominator?

Practice

Make it your own

Write a sentence using “least common denominator”, then check it and compare it with the examples above.

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